Conventionally, bonding sheets have been used for bonding boards including flexible printed circuit (FPC) boards and components such as electronic components, mechanical components and optical components to other components such as liquid crystal display (LCD) board or plasma display panel (PDP) board. For example, anisotropic conductive film sheets (hereinafter, referred to as ACF sheets) have been used for mounting FPC boards on LCD board.
An ACF sheet is formed by including an epoxide-based synthetic resin containing conductive metal particles mixed therein and is capable of bonding two members. An FPC board can be mounted on an LCD board using an ACF sheet through the following three processes, in general. In a first process, the ACF sheet is supplied to a predetermined applying position on a side of the LCD board at a state where a base material layer is adhered to the upper surface of the ACF sheet with the bonding force (adhesive force) of the ACF sheet itself. Subsequently, the ACF sheet is applied at its lower surface to the applying position and the base material layer on the upper surface of the ACF sheet is stripped. In a second process, the FPC board is aligned to the LCD board and then is temporarily pressed and adhered to the ACF sheet on the LCD board. In a third process, the FPC board is completely pressed and applied to the LCD board.
However, the first process has had the issue of the tendency to induce application failures and stripping failures around the positions at which the stripping was started and ended, after the application of the ACF sheet to the applying position and the stripping of the base material layer from the ACF sheet. Further, in recent years, boards such as LCD board and PDP board have tended to be increased in sizet hereof. Along therewith, ACF sheets have been applied to only mounting positions after being divided into points, in order to eliminate the waste of the ACF sheets. Accordingly, ACF sheets have been applied to a single board at a greater number of positions thereon, which has increased the number of positions at which inspections should be performed for determining whether the applied state of ACF sheets is favorable or unfavorable. For example, in mounting components on a board with a size of 37 inches, the number of components to be mounted along a single side of the board is about 3 to 12, which requires performing inspections at least at 14 or more positions on the single board. Accordingly, if an operator performs visual inspections for determining whether the applied state is favorable or unfavorable as in the conventional art, this will require large time and manpower for the inspections.
Japanese Patent Publication No. 3324599 (Patent Document 1) discloses an apparatus and a method for improving the issue. The apparatus and the method of the Patent Document 1 employ an recognition means including a camera for automating inspections of the applied state of a conductive film (ACF sheet) adhered to a display panel such as an LCD, to enable the inspections with accuracy in a short time. More specifically, the following operations are conducted.
First, a plurality of ACF sheets having a base material layer adhered thereon are applied to a single board. Thereafter, only the base material layers are stripped from a plurality of the ACF sheets. Then, the applied state of the plurality of the ACF sheets applied to the single board is inspected, using the recognition means including the camera. If the inspection reveals an application failure or stripping failure even at only a single position, an applying operation or a stripping operation is conducted again at the position of the application failure or stripping failure, and then, an inspection is conducted again. The operation is repeated a predetermined number of times, in order to eliminate application failures or stripping failures in the ACF sheet.